Cells + internal environment Flashcards
What are the different components of the body? + their %?
- 60% water- decreases with age
- 18% protein
- 15% fat
- 7% minerals
Name + define all of the body fluid compartments
Interstitial fluid = thin layer of fluid outside of cells
Blood plasma = all fluid within blood vessels
Intracellular fluid = fluid inside of cells
What 2 body fluid compartments make up the extracellular fluid?
Blood plasma + interstitial fluid
What is the proportion of water in each body fluid compartment?
1/3 water in extracellular parts- mostly interstitial fluid
2/3 water in intracellular fluid
Define: Osmotic Equilibrium
Water can move across different compartments until it reaches the same concentration across them all
In what ways can water be lost or gained?
+ Stomach + intestines via eating and drinking
+ Blood vessels
- Vomiting and diarrhoea
- Bleeding
- Respiration
- Kidneys via urine
In what ways can water be lost or gained?
+ Stomach + intestines via eating and drinking
+ Blood vessels
- Vomiting and diarrhoea
- Bleeding
- Respiration
- Kidneys via urine
Describe the structure of the cell membrane
Phospholipid bilayer = double layer of phospholipid molecules:
- hydrophobic tails = 2 fatty acid chains
- Hydrophillic heads = love water
transmembrane proteins form holes throughout membrane
What model is the cell membrane structure usually reffered to as? + why?
Fluid-Mosaic Model:
- fluid = molecules held together by van der waals forces so they can move
- Mosaic = proteins present
What are the functions of the cell membrane?
- Structure for cell- in aqueous solution lipids organise into spheres
- Controls intracellular environment- creates a chemical disequilibrium as it has different permeability to different molecules
Define: chemical disequilibrium
= different conc of molecules in and out of cell
What molecules lead to a chemical disequilibrium of body fluid compartments?
+ Which ones are higher in conc in the intracellular fluid and extracellular fluid?
Intracellular = + potassium, calcium, protein
Extracellular = + sodium, chlorine
What factors affect permeability and why?
- size = smaller molecules = more permeable
- lipid solubility = more permeable
- charge = membrane less permeable
Define: Diffusion and what is it caused by?
= movement from one area of high concentration where there is more collisions to low concentration where there is less collisions
- caused by random collisions of molecules travelling at high speeds
Where can diffusion take place?
open systems
or
Boundary between 2 systems
Define: osmosis
= movement of water molecules from a high to low conc in response to a solute concentration gradient to balance water levels
Define: osmotic pressure
= pressure needed to prevent movement of water
Are the fluid compartments usually in a state of equilibrium or disequilibrium?
Osmotic equilibrium
What is the function of proteins in cell membranes?
Act as carriers of channels to facilitate flow of substances that cannot permeate the lipid bilayer e.g. ions, larger molecules
Define: facilitated diffusion
movement of molecules from high to low conc down the concentration gradient using protein carriers or protein channels
How do protein carriers work?
proteins combine to a specific substrate and carries it across cell membrane, where it releases into cell
How do protein channels work?
Protein spans across entire membrane and allows movement of substances e.g. ions when open
What are aquaporins?
Water channels that move water molecules in a single file via osmosis
Define: active transport
Movement of molecules from low to high concentration against the concentration gradient- so energy is required
Where does energy for active transport come from?
ATP which is broken down into ADP via ATPase which releases energy
Define: endocytosis
movement of substances into cell
Name and define 2 types of endocytosis
Pinocytosis = molecules get trapped within vesicles within membrane and are brought into cell
Phagocytosis = arms of cytoplasm encapsulates molecules and brings inside of cell
Define: exocytosis + how does it work?
= movement of substances out of cells
- moves hormones + neurotransmitters out of cells via vesicles that fuse with cell membrane to be released outside of cell
